Time-Varying Analysis and Precise Prediction of Lunar Physical Libration Parameters
Lunar libration is the actual oscillations of the Moon in space,deviating from the ideal situation. They are closely related to the establishment of the lunar coordinate sys-tem,the conversion between the lunar and terrestrial coordi-nate systems,and the positioning of lunar landers. They also reveal to some extent the internal structure and physical prop-erties of the Moon. Currently,the prediction of lunar libra-tions is mainly based on JPL ephemeris model data,but the accuracy of the predictions is low. This study is based on the measured data from the Chang'e 3 lunar lander to investigate the prediction method for lunar librations. To address the is-sue of low local resolution in Fourier transform,a combina-tion of wavelet decomposition and fast Fourier transform is used to extract a total of 11 periodic terms of lunar librations. Furthermore,it is confirmed that the periodic terms of lunar li-brations are not only influenced by the gravity of the Sun and Earth but also related to lunar seismic activity. Based on the extracted periodic terms,both the ARIMA model and sine function fitting are employed to predict lunar librations. The results indicate that the ARIMA model is only suitable for short-term predictions,while the sine function fitting with fre-quency division is the batter predictions method.
lunar librationperiodic signalARIMAtime-varying analysissinusoidal function
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万方数据
